I would defiantly test the flow NTC (thermistor) first before forking out for a pcb!! I can't comfirm but from what you've described then it's not likely to be a pcb fault as from my experience if your hw is fine and ch faulty or vice versa then it's not normally the pcb at fault. What are the...
With unvented hot water systems a pressure reducing valve is fitted to balance out the hot and cold water flow rates. It's a common fault for these to go faulty and start causing water pressure problems. But also just make sure severn Trent water aren't doing any works in your area, sounds daft...
Its hard to diagnose without being there but if you isolate the cold main supply on the boiler then all hot outputs should stop. To trace the reason why the hot tap still runs with the boiler cold main isolated you need to look at any part of the cold main circuit meets the hot. Mixer showers...
Hi there!
The hot water pipe circuit shouldn't be directly connected to the cold main circuit only via mixer showers, taps etc... if you turn off the cold water inlet isolation to the boiler then this should turn off the supply to all hot water outlets in the property.
Jay
Yes you can turn your heating back on no problem, make sure the radiator is connected back to the valves and shut off the other valve on the radiator to make sure the air doesn't get out of the radiator and into the rest of your heating system.